Point Source Technique for Gamma Ray Absorption Studies.

1962 ◽  
Vol 34 (4) ◽  
pp. 585-586 ◽  
Author(s):  
Joseph Bubernak ◽  
M. S. Lew ◽  
G. M. Matlack
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Absorption Studies

scholarly journals Exploration of the high-redshift universe enabled by THESEUS

2021 ◽  
Author(s):  
N. R. Tanvir ◽  
E. Le Floc’h ◽  
L. Christensen ◽  
J. Caruana ◽  
R. Salvaterra ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Star Forming ◽  
Chemical Enrichment ◽  
Long Duration ◽  
Absorption Studies ◽  
Population Iii Stars ◽  
High Redshift Universe

AbstractAt peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar and intergalactic medium back to the reionization era. The proposed THESEUS mission is designed to detect large samples of GRBs at z > 6 in the 2030s, at a time when supporting observations with major next generation facilities will be possible, thus enabling a range of transformative science. THESEUS will allow us to explore the faint end of the luminosity function of galaxies and the star formation rate density to high redshifts; constrain the progress of re-ionisation beyond $z\gtrsim 6$ z ≳ 6 ; study in detail early chemical enrichment from stellar explosions, including signatures of Population III stars; and potentially characterize the dark energy equation of state at the highest redshifts.

Point-Source Gamma Ray Standards

Radiology ◽  
1960 ◽  
Vol 74 (1) ◽  
pp. 120-121
Keyword(s):  
Point Source ◽  
Gamma Ray

scholarly journals Determination of Gamma-ray Efficiency Curves for Volume Samples by the Combination of Monte Carlo Simulations and Point Source Calibration

2000 ◽  
Vol 37 (12) ◽  
pp. 1075-1081 ◽  
Author(s):  
Jun SAEGUSA ◽  
Tetsuya OISHI ◽  
Katsuya KAWASAKI ◽  
Michio YOSHIZAWA ◽  
Makoto YOSHIDA ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Point Source ◽  
Monte Carlo Simulations ◽  
Gamma Ray

scholarly journals Searching for Gamma-Ray Millisecond Pulsars: Selection of Candidates Revisited

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 31
Author(s):  
Xuejie Dai ◽  
Zhongxiang Wang ◽  
Jithesh Vadakkumthani
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Previous Analysis ◽  
Test Statistic ◽  
Large Area ◽  
Millisecond Pulsars ◽  
Multi Wavelength ◽  
Γ Ray ◽  
Available Information ◽  
Selection Of

We are starting a project to find γ -ray millisecond pulsars (MSPs) among the unidentified sources detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope (Fermi), by radio observations. The selection of good candidates from analysis of the LAT data is an important part of the project. Given that there is more than 10 years worth of LAT data and the advent of the newly released LAT 8-year point source list (FL8Y), we have conducted a selection analysis, on the basis of our previous analysis, and report the results here. Setting the requirements for the unidentified sources in FL8Y of Galactic latitudes | b | > 5 ∘ and curvature significances >3 σ , there are 202 sources with detection signficances >6 σ . We select 57 relatively bright ones (detection significances >15 σ ) and analyze their 10.2 years of LAT data. Their variability is checked to exclude variable sources (likely blazars), test statistic maps are constructed to avoid contaminated sources, and curvature significances are re-obtained and compared to their γ -ray spectra to exclude non-significant sources. In the end, 48 candidates are found. Based on the available information, mostly from multi-wavelength studies, we discuss the possible nature of several of the candidates. Most of these candidates are currently being observed with the 65-meter Shanghai Tian Ma Radio Telescope.

scholarly journals Millisecond Pulsars in the Galactic Bulge? An Extended Discussion on the Wavelet Analysis of the Fermi-LAT data

2016 ◽  
Vol 11 (S322) ◽  
pp. 193-196
Author(s):  
Richard Bartels ◽  
Christoph Weniger
Keyword(s):  
Dark Matter ◽  
Spectral Analysis ◽  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Point Source ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Supportive Evidence ◽  
Millisecond Pulsars ◽  
Extended Discussion

AbstractA clear excess in the Fermi-LAT data is present at energies around a few GeV. The spectrum of this so-called ’GeV excess’ is remarkably similar to the expected annihilation signal of WIMP dark matter. However, a large bulge population of millisecond pulsars living below the Fermi–LAT detection threshold could also explain the excess spectrum. In a recent work we optimized the search for sub-threshold sources, by applying a wavelet transform to the Fermi–LAT gamma-ray data. In the Inner-Galaxy the wavelet signal is significantly enhanced, providing supportive evidence for the point source interpretation of the excess. In these proceedings we will extent our previous work with a spectral analysis and elaborate on the potential contamination from substructures in the gas.

Gamma-ray absorption studies in some scheelites

1982 ◽  
Vol 1 (7) ◽  
pp. 310-311
Author(s):  
S. K. Arora ◽  
R. S. Godbole ◽  
G. S. Trivikrama Rao
Keyword(s):  
Gamma Ray ◽  
Absorption Studies

Guaranteed Unresolved Point Source Emission and the Gamma-ray Background

2007 ◽  
Author(s):  
Vasiliki Pavlidou ◽  
Jennifer M. Siegal-Gaskins ◽  
Brian D. Fields ◽  
Angela V. Olinto ◽  
Carolyn Brown
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Source Emission

scholarly journals Constraints on the optical-IR extragalactic background from γ-ray absorption studies

2011 ◽  
Vol 7 (S284) ◽  
pp. 420-428 ◽  
Author(s):  
Luigi Costamante
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Background Light ◽  
Radiation Fields ◽  
Direct Measurements ◽  
Absorption Studies ◽  
Diffuse Background ◽  
Very High Energy ◽  
Tev Gamma Rays ◽  
Very High

AbstractVery high energy (VHE ≳0.1 TeV) gamma-rays from extragalactic sources, interacting by γ-γ collisions with diffuse intergalactic radiation fields, provide an alternative way to constrain the diffuse background light, completely independent of direct measurements. The limits depend however on our knowledge of the physics of the gamma-ray sources. After clarifying the interplay between background light and VHE spectra, I summarize the extent and validity of the obtainable limits, and where future improvements can be expected.

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